JPS59164150A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To make it possible to dissolve a problem caused by the shift of a bonding position, by providing a groove, which has a width being 5-30% on the basis of that of a pressure chamber, to the thin plate of an electromechanical converter so as to surround a position where a piezoelectric element must be bonded while bonding said element to the position surrounded by said groove. CONSTITUTION:A groove 501 is provided to the upper plate 102 on the pressure generating chamber 104 formed to a substrate 100 at the bonding position of a piezoelectric element 103 so as to leave a width bp by etching. When the width bp' of the piezoelectric element 103 is made slightly wider than the width bp and made almost equal to the width bi of the pressure generating chamber 104, the piezoelectric element 103 is bonded to the upper plate 102 in the width bp occupying 70-90% of the width bp' and the deformation amount thereof comes to about 2.3 times as compared with a conventional one is determined by the width bp of the groove 501 regardless of the width of the piezoelectric element. Therefore, the deformation amount is not changed even if the shift of the bonding position is generated and the processing numbers accompanying the determination of the bonding position can be reduced and the jet efficiency of ink droplets can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drop-on-demand type inkjet recording head.

The recording head used in a drop-on-demand inkjet printer is shown in cross-sectional view (a) and top view (b) in Figure 1.
A substrate 100 consisting of an ejection channel system having a pressure generation chamber (hereinafter referred to as pressure chamber) 104 between a nozzle hole 101 and an ink reservoir 105 shown in FIG. A piezoelectric element 103 made of zircon titanate, barium titanate, etc. is connected to the upper plate 1.
02 at a position corresponding to the pressure chamber 104 using an adhesive, diffusion bonding, or other means.

A variation of the same structure is disclosed in patent number M57-071983 ``Multi-nozzle print head'' issued by the same applicant.

Now, the operating principle of the recording head is that when an electric signal is applied to the piezoelectric element 103 in accordance with a recording signal from an electronic computer or a communication line, a portion of the upper plate 102 corresponding to the pressure chamber 104 is formed by a bimetallic material between the piezoelectric element 103 and the upper plate 102. The effect causes it to bend and deform instantly. As a result, the volume of the pressure chamber 104 decreases momentarily, and the ink supply pipe 1
A pressure wave is generated in the ink inside the pressure chamber 104 filled from the outside via the ink. The pressure wave causes the nozzle hole 1 to
One ink droplet 107 is ejected from 01.

By the way, in FIG. 2 showing the cross section A-A in FIG. 1(b), the width of the piezoelectric element 103 is the width bi of the pressure chamber 104.
When the ratio of bp/b is between 07 and 0.9, the amount of deformation is largest, so this recording head has bI
)/bi = 0.7 to 0.9. This has become clear from the results of numerical calculations using the finite element method model shown in FIG. FIG. 3 shows the left half region of the cross-sectional view of FIG. 2 divided into finite elements, and the dotted line 3 in the figure is the deformation curve based on the calculation result. As a result of examining the amount of deformation δ using the width bp as a parameter, the graph shown in FIG. 4 is obtained, and the maximum point 4 of the amount of deformation δ is in the range of /b=0.7 to 0.9.

Strictly speaking, the value of b p /b i is the width bi of the pressure chamber,
Although it varies depending on the thickness t9 of the piezoelectric element and the thickness t1 of the upper plate, it is in the range of 0.7 to 0.9. However, this is on the condition that the piezoelectric element 103 is accurately bonded to the center of the pressure chamber 104. If the piezoelectric element 103 is slightly shifted from the existing position, that is, if it is bonded to an asymmetrical position, the amount of deformation δ decreases, resulting in a problem that the ejection efficiency of ink droplets deteriorates. Further, the piezoelectric element 103 is connected to the upper plate 1.
When bonding to 02, it is very difficult to accurately bond at the above position even with the use of jigs, and there is a problem in that manufacturing costs such as increased man-hours are significant. .

An object of the present invention is to use a simple configuration to solve problems caused by misalignment of the bonding position between the upper plate and the piezoelectric element, and to improve the ejection efficiency of ink droplets.

According to the present invention, the 1 comprises a nozzle hole and a pressure generating chamber.
or a plurality of ejection channel systems are configured to communicate with one common ink reservoir, and during recording, an electromechanical transducer provided at a position corresponding to the pressure chamber is deformed, and ink is ejected from the nozzle hole. In a drop-on-demand type ink jet recording head, a thin plate of an electromechanical transducer consisting of a thin plate and a piezoelectric element has a groove having a width of 5 to 30% of the width of the pressure chamber around the bonding position of the piezoelectric element. An inkjet recording head characterized in that a piezoelectric element is bonded to a position surrounded by the groove can be obtained.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a block diagram of the inkjet recording head of the present invention, and FIG. 6 is a diagram showing a cross section EB in FIG. 5.

Now, at the bonding position of the piezoelectric element 103 shown in FIG. 5, a groove 501 is provided by etching or machining the outer periphery so as to leave the above-mentioned width bB. As shown in FIG. 6, the widths 'b,' of the piezoelectric element 103 are set to be slightly wider than the width bp. Further, the width bp' may be the same as the width bi of the pressure chamber. If b,'=b,
If so, 70 to 90 of the width bp' of the piezoelectric element 103
- The width bp is joined to the upper plate 102, and the other parts are floating on the groove 501 on the upper plate 102. Further, the thickness of the groove 501 is thinner than the thickness ti of the other portions, and therefore the rigidity is low. As shown in FIG. 7, this was modeled using the finite element method in the same manner as in FIG. If tp/li is taken as a parameter, the amount of deformation δ becomes as shown in the graph of FIG. The dotted line 8a in the figure is the result obtained by the conventional electromechanical converter shown in FIG. 2, and the solid line 8b is the result obtained by the electromechanical converter of the present invention shown in FIG.

As can be seen from FIG. 8, the deformation amount of the present invention is about 2.3 times that of the conventional one (the depth of the groove 501 is 1/2 of the thickness t of the upper plate, b, / b, -〇, 8)
It has become clear that it is possible to obtain a large amount of Regarding the width, the amount of deformation is determined by the width bp of the joint portion set by the groove 501, regardless of the width bp' of the piezoelectric element 103. Therefore, it is clear that even if the piezoelectric element 103 is misaligned with respect to the pressure chamber 104, there will be no problem with the amount of deformation as long as the width of the joint is secured. In actual experiments, the above-mentioned contents were confirmed, and the effect was significant.

As explained above, the inkjet recording head of the present invention has a simple configuration and can solve the problem caused by misalignment of the bonding position of the piezoelectric element with respect to the upper plate, so that the manufacturing man-hours associated with bonding positioning can be reduced. Moreover, an inkjet recording head with high ink droplet ejection efficiency can be realized, and is extremely useful.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional inkjet recording head, (a) is a side sectional view, (b) is a top view, FIG. 2 is a sectional view of an electromechanical transducer of a conventional inkjet recording head, and FIG. 3 is a diagram of a conventional inkjet recording head. is a diagram of the finite element method model shown in Fig. 2, Fig. 4 is a graph of the calculation results of the model shown in Fig. 3, Fig. 5 is a block diagram of the inkjet recording head of the present invention, and Fig. 6 is the inkjet recording head of the present invention. 7 is a finite element method model diagram of FIG. 6, and FIG. 8 is a graph of calculation results of the conventional one and the one of the present invention. In the figure, 102 is an upper plate, 103 is a piezoelectric element, 104 is a pressure generating chamber, and 501 is a groove. (b) Figure 3 Island Figure 4 o o, so7-o, qr. bp/bL Fig. 6 Fig. 4/UIJ-100 Fig. 8 tJp/lr

Claims (1)

[Claims] One or more ejection channel systems each having a nozzle hole and a pressure generating chamber are configured to communicate with one common ink reservoir, and an electric current is provided at a position corresponding to the pressure generating chamber during recording. In a drop-on-demand inkjet recording head that deforms a mechanical transducer and ejects ink from the nozzle hole, a bonding position of the piezoelectric element is formed on the plate of the electromechanical transducer consisting of a thin flat plate and a piezoelectric element. An ink jet recording head having a groove having a width of 5 to 30% of the width of the pressure generating chamber around the pressure generating chamber, and a piezoelectric element bonded to a position surrounded by the groove.